Makoto Nonaka

Ia ANTIGENS ON SUPPRESSOR, AMPLIFIER AND HELPER T CELLS

Publisher Summary This chapter discusses Ia antigens on suppressor, amplifier, and helper T cells. Some, but not all, functional subsets of T cells express Ia antigens on their cell surface, and the molecules play substantial roles in a variety of regulatory cell interactions. It has been demonstrated that the treatment of T cells with anti-Ia antisera removes various functions of T cells and that some of the regulatory T cell-derived factors are absorbed with anti-Ia antisera. These include helper and suppressor T cells and the factors liberated from them. The presence of Ia antigens on T cells has been demonstrated mainly by two different approaches. Some of them are determined as antigen-specific T cell factors carrying determinants reactive with anti-Ia antisera, and others are detected on cell-surface membrane as evidence by the removal of certain functions after cytotoxic treatment of T cells with anti-Ia antisera. Results obtained in various studies indicate that T cell Ia antigens are a series of polymorphic cell surface molecules controlled by closely linked multiple I region loci whose expression is directly related to the function born by the T cell subset.

HELPER T CELLS EXPRESSING AN I-J SUBREGION GENE PRODUCT

ABSTRACT The locus in the I-J subregion coding for a serological marker on nylon wool-adherent helper T cells (Th 2 ) was shown to be distinct from the locus which controls Ia determinants selectively expressed on Lyt-2 + , 3 + suppressor T cells. The Ia + helper T cell (Th 2 ) showed a number of characteristics that distinguish it from the conventional Ia − helper T cell (Th 1 ). Th 2 was extremely sensitive to the ionizing radiation or the treatment with mitomycin C in contrast to the relative resistance of Th 1 against these treatment. Th 2 did not cooperate efficiently with B cells having low Ia antigen, while Th 1 stimulated B cells that were resistant to anti-Ia treatment. The effect of Th 2 was directly suppressible by carrier-specific suppressive T cell factor, whereas effect of Th 1 was not. These results indicate that the mode of help given by Ia + and Ia − helper T cells is different.